Irrigation system

ABSTRACT

The invention relates to a distribution system for subsurface or trickle irrigation of arid land using plastic pipe with spaced wall slits therein. Spring clips encircle the pipe at each slit to define pressure-initiated opening of each slit and the subsequent closure thereof. The pressure of the system may be increased to bring about opening of the slits with the resultant exit of water from each slit. More uniform water distribution results from use of this system and longer runs of piping may be used. Also, occasional application of higher pressure minimizes blockage of the slits by foreign particles.

iinited States Patent [191 Hammond et al.

[ 1 JuneS, 1973 [54] IRRIGATION SYSTEM [22] Filed: Feb. 23, 1972 [21]Appl. No.: 228,676

[52] US. Cl ..61/12 [51] Int. Cl. ..E02b 13/00 [58] Field of Search..61/12, 13;

[56] References Cited UNITED STATES PATENTS FOREIGN PATENTS ORAPPLICATIONS Great Britain ..61/12 Australia ..61/12 PrimaryExaminer-David J. Williamowsky Assistant Examiner-David H. CorbinAtt0rneyRoland A. Anderson 57 ABSTRACT The invention relates to adistribution system for subsurface or trickle irrigation of arid landusing plastic pipe with spaced wall slits therein. Spring clips encirclethe pipe at each slit to define pressure-initiated opening of each slitand the subsequent closure thereof. The pressure of the system may beincreased to bring about opening of the slits with the resultant exit ofwater from each slit. More uniform water distribution results from useof this system and longer runs of piping may be used. Also, occasionalapplication of higher pressure minimizes blockage of the slits byforeign particles.

4 Claims, 3 Drawing Figures PATENTEDJUN 5 I975 SHEET 2 BF 2 WATER SOURCEHYDRAULIC PULSER BACKGROUND OF THE INVENTION This invention was made inthe course of, or under, a contract with the United States Atomic EnergyCommission.

Except for flooding techniques, surface sprinkling is probably theoldest means used for irrigation. This may be accomplished from fixedinstallations or, with sectional piping, from movable systems. Thelatter has economic advantages in that irrigation can be accomplished inspecific areas and then moved as needed. It may be removed for plowing,cultivating and the like. With rising labor costs, this advantage maynot be as large as in years past. The system also has certaindisadvantages; probably the greatest is the nonuniformity ofdistribution. This nonuniformity results from windinduced distortion ofthe spray pattern and leads to the necessity to apply more water to partof the area than is needed so as to assure adequate amounts in otherareas. In addition, evaporation in the air and from the soil surfacefurther reduce efficiencies of water utilization. If fertilizer isapplied with the water, or on the surface, run-off of the water givesrise to potential pollution of streams, etc.

Subsurface and trickle irrigation, on the other hand, are efficientmethods for the application of water for irrigation. The water isapplied more directly to plant roots and little is lost by evaporationexcept by transpiration through foliage where it is desired. Soilsurface losses may be minimized by mulches, etc., These systems havebeen investigated in recent years as costs of pipe, particularly plasticpipe, have been reduced. An extensive survey of the literature in thisfield has been compiled and has been published in a Government Report,ORNL-NDIC-9, November 1971, and entitled Subsurface And TrickleIrrigation A Survey Of Potentials And Problems.

In general the prior art has utilized plastic pipe, with some sort ofwall opening, as laterals from a header. Punched or drilled holes,slots, orifice inserts, or general wall porosity have been used. All ofthe openings must be small enough to restrict the flow sufficiently inorder to operate at a relatively high water pressure and thus maintain alow ressure drop along the lateral line. With holes or slots, problemsof nonuniform distribution have been encountered; and with all types,gradual plugging of the openings has occurred from various causes.

Thus, there exists a need for a more effective and efficient system forirrigating arid areas using subsurface or trickle techniques. Thepresent invention was conceived to meet this need in a manner to bedescribed hereinbelow.

SUMMARY OF THE INVENTION It is the principal object of the presentinvention to provide a tubing arrangement and an operating system tomore economically and effectively irrigate arid areas using subsurfaceor trickle techniques.

The above object has been accomplished in the present invention byproviding a water distribution system employing a slitted plastic pipeor pipes, using a mechanical spring member at each slit whereby openingat a given pressure is assured as well as increasing the closingpressure; and using a pressurized fluid operation so that the slits areopened more or less uniformly.

Occasional bursts of water flow aid in clearing any de bris from theslit. These features combine to produce more uniform water distributionall along a lateral of the irrigation system and permit use of longerlaterals for greater efficiencies than heretofore possible.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric sketch of aportion of a waterdistributing pipe illustrating various embodiments ofspring clips suitable for controlling exit of water from slits in thepipe;

FIG. 2 is a sketch of an overall water distribution system using thedesign of FIG. 1 or FIG. 3,and

FIG. 3 is a cross-sectional drawing of a possible embodiment for use asa trickle irrigation device in the system of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The spring closure concept ofthe present invention is illustrated in FIG. 1, which shows severalembodiments of spring clips that may be utilized. A plastic pipe ortubing 10 is shown provided with slits 11-13. Typically the pipe may be0.5 inch ID. with l/16 inch wall thickness, with slits placed every12-24 inches along the pipe. Slits 11 and 12 are assumed to beidentical; slit 13 is modified, to overcome tearing if such is theproblem, with small-radii holes 14 at each end of the slit. At slit 11is illustrated a spring clip 15 fabricated from circular spring stock.Each end of clip 15, as in the case of the other embodiments, may beslightly curved away from the pipe surface to prevent cutting thesurface thereof during installation and subsequent operation. A flatspring clip 16 is illustrated at slit l2, and a double clip 17, with oneor more connecting links 18 is shown at slit 13. Although the operatingcharacteristic would be affected, the clips may be oriented so as tocross over the slits, if desired. It should be understood that in agiven installation, identical slits would be utilized as well asidentical spring clips and orientation with respect to the slits. Theonly variations might be the spacing of the slits and the springconstant of the clips to effect a desired water distribution pattern.

FIG. 2 is an illustration of an irrigation system utilizing the tube andclip design of FIG. 1 or FIG. 3. A source of water 20 provides water toa circulating pump 21 unless sufficient head is provided by the source20, and then pump 21 may be omitted. Water is supplied to a main header22 to which are connected a plurality of lateral lines 23 of the typeshown in FIG. 1. These laterals may be spaced 3-6 feet apart and may beup to 1,500 feet in length. Furthermore, at least a portion of thelaterals may be connected at their opposite end to an auxiliary header24 for the purposes to be described hereinbelow. The slit openings andassociated spring clips in the lateral lines 23 of FIG. 2, not shown forthe sake of clarity, may be spaced apart in each of the lateral lines bya distance of 12-24 inches with each slit being one-half inch long, forexample. It should be noted that the lateral lines 23 are smaller indiameter than the headers 22 and 24 in the actual installation of thissystem.

Attached to the header 22, and effectively to auxiliary header 24, is ahydraulic pulser 25. This provides pulses of sufficient pressure toproduce high velocity flow of water through the slits, not shown, inlaterals 23. For example, the pressure peaks may be about an additional6-8 psi above the normal pressure of the system. Pulser 25 is controlledby a timer 26, or other device, to give the desired flow of waterthrough slit openings at desired time intervals.

No showing is made in FIG. 2 of the valves and other conventionalancillary equipment. One valve that may be desired in the system of FIG.2 would provide for feeding a portion of the water through auxiliaryheader 24. This would provide a certain flushing action and wouldovercome nonuniform distribution if pressure drop along a lateral line23 is large enough to otherwise cause nonuniform water distribution.Although not shown, alternate laterals may be connected to the header 22and the others to auxiliary header 24. Alternatively, the plasticlaterals 23 could be sealed off at the end opposite the distributionheader and thus considerable savings in extra header costs would berealized.

At least two modes of operating the system of FIG. 2 are available foruse depending upon the particular needs of the installation. In onemode, the pressure of the source 20 or pump 21 may be of the order of3-5 psi. This is insufficient to open slits in the piping. Periodically,at either a uniform or nonuniform frequency, the pulser 25 would beoperated to bring about water flow through the slits. In the second, andprobably preferred mode, the pressure in the system would be maintainedconstant at 10-20 psig (slits open) for a given time period, e.g., 12hours, and then reduced to at least a value to close the slits. Once perday, for example, an

additional 6-8 psi would be applied by pulser 25 to produce a cleaningaction at each slit opening.

The distribution system of FIG. 2 may be utilized underground (forsubsurface irrigation) with pipe as illustrated in FIG. 1, or on thesurface (for trickle irrigation) with pipe as illustrated in FIG. 3. InFIG. 3, a pipe 30, having spaced slits 31 is attached to a mulch flap32. The slits 31 are oriented downward, and each slit is normally heldin a closed position by a spring clip 33. Flap 32 may extend laterallyto near each row of a row crop to prevent excessive evaporation into theatmosphere. Furthermore, this structure is suitable for the distributionof gaseous fertilizer, such as C0 to the plant foliage.

The embodiments of either FIG. 1 or FIG. 3 may be provided with a riser,not shown, at certain intervals to spray the surface of the ground. Thismay be desirable to aid the germination of seeds or cool the foliage ofplants. Such risers would contain a pressure-operated valve set at, forexample, a higher pressure than required for opening the pipe slits.Furthermore, these risers might be provided with a gas-release trapuseful for bleeding air from the system and/or the distribution of C0The advantages of the system described hereinabove are as follows:

1. Closure pressure, and thus opening pressure, are governed by thespring clips rather than the pipe wall resiliency. Thus, it isselectable and is predictable over the life of the installation.

2. Pressure pulses will increase the flow through the slits as they openand thus the slits will tend to be selfcleaning.

3. Pulse waves travel with the speed of sound, thus all slits tend toopen simultaneously.

4. The system permits gaseous fertilizer application therethrough.

5. Because of l and 3 above, operating pressure is increased and therelative pressure drop along each lateral is reduced permitting lateralsof about 1,000 feet or longer in length (compared to about 100 feet inthe prior art).

6. The system is adaptable to mechanized installation including slittingand application of the spring clips.

7. The system provides for a reduction in pollution via run-off,atmospheric evaporation, loss of fertilizer, etc.

8. The system achieves cost reduction through increased efficiency ofwater use, lower installed system costs and savings from operatingcosts.

The system of the present invention can be economically used forlarge-scale agricultural projects located on coastal deserts, forexample, with energy for power generation and desalination beingsupplied by dualpurpose nuclear-powered reactors which can be built atlocations relatively independent of local sources of fuel.

The present invention has been described by way of illustration ratherthan limitation and it should be apparent that it is equally applicableto all areas where there exists a definite need for irrigation.

What is claimed is: v

1. An improved system for the irrigation of arid land comprising asource of water; an elongated, hollow header coupled to said watersource; a plurality of hollow, elongated, lateral lines coupled to andin communication with said header, each of said lateral lines providedwith a plurality of spaced-apart and normally closed slits; a pluralityof spring clips encompassing each of said lateral lines with respectiveones of said clips encompassing each of respective ones of said slits insaid lines, each of said clips having each end thereof slightly curvedaway'from the associated lateral line; means for supplying water fromsaid source to said header and to the associated lateral lines at somese lected pressure value; all of said clips being identical and all ofthem having the same spring constant, said spring clips maintaining saidrespective slits closed in the absence of water pressure to said laterallines, whereby when said selected pressure value is applied to saidheader and to said lateral lines, said spring constant of each of saidclips is overcome to open all of said slits substantially simultaneouslythereby effecting a substantially uniform distribution of water throughall of said lateral line slits for the effective uniform irrigation ofsaid land with which said header and lateral lines areassociated. 2. Thesystem set forth in claim I, and further including a timed, hydraulicpulser coupled to said header and thus to said lateral lines to providepulses of an additional pressure at selected time intervals forproviding a periodic cleaning or flushing action at each slit opening.

3. The system set forth in claim 1, wherein said header and laterallines are plastic and are placed u'nderground for sub-surfaceirrigation.

4. The system set forth in claim 1, wherein said header and laterallines are plastic and are placed on the ground surface for trickleirrigation, said system further including a mulch flap attached to andcompletely covering each of said lateral lines with the slits of eachlateral line oriented downward.

1. An improved system for the irrigation of arid land comprising asource of water; an elongated, hollow header coupled to said watersource; a plurality of hollow, elongated, lateral lines coupled to andin communication with said header, each of said lateral lines providedwith a plurality of spaced-apart and normally closed slits; a pluralityof spring clips encompassing each of said lateral lines with respectiveones of said clips encompassing each of respective ones of said slits insaid lines, each of said clips having each end thereof slightly curvedaway from the associated lateral line; means for supplying water fromsaid source to said header and to the associated lateral lines at someselected pressure value; all of said clips being identical and all ofthem having the same spring constant, said spring clips maintaining saidrespective slits closed in the absence of water pressure to said laterallines, whereby when said selected pressure value is applied to saidheader and to said lateral lines, said spring constant of each of saidclips is overcome to open all of said slits substantially simultaneouslythereby effecting a substantially uniform distribution of water throughall of said lateral line slits for the effective uniform irrigation ofsaid land with which said header and lateral lines are associated. 2.The system set forth in claim 1, and further including a timed,hydraulic pulser coupled to said header and thus to said lateral linesto provide pulses of an additional pressure at selected time intervalsfor providing a periodic cleaning or flushing action at each slitopening.
 3. The system set forth in claim 1, wherein said header andlateral lines are plastic and are placed underground for sub-surfaceirrigation.
 4. The system set forth in claim 1, wherein said header andlateral lines are plastic and are placed on the ground surface fortrickle irrigation, said system further including a mulch flap attachedto and completely covering each of said lateral lines with the slits ofeach lateral line oriented downward.